The present invention relates generally to frequency divider circuits, and more specifically to digital frequency divider circuits.
Many applications exist for frequency synthesizers. For example, in communications systems, frequency synthesizers can be used to generate local oscillator (LO) signals for modulating and demodulating radio frequency (RF) signals. In these systems, the RF signals can be varied in frequency by varying the frequency of the LO signals.
A frequency synthesizer with a variable output frequency may utilize a feedback loop circuit that includes frequency divider circuits, or xe2x80x9cprescalers.xe2x80x9d A frequency prescaler typically employs a combination of sequential elements and digital logic to provide a variable amount of frequency division. For example, a frequency prescaler may be configured to divide a reference signal by a factor of 4 or by a factor of 5 using flip-flops and digital logic gates. By varying the amount of frequency division provided by the prescaler, the synthesizer output frequency can be varied.
Any given frequency synthesizer has a maximum frequency at which it will reliably operate. This maximum frequency is dependent on many factors, including the topology of the circuit, the underlying manufacturing process, and the maximum operating frequency of the prescaler. If a faster prescaler is available, this may increase the maximum operating frequency of the frequency synthesizer.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternate frequency division mechanisms.